Base station device, mobile station device, program, uplink synchronization requesting method, and synchronization-shift measurement signal transmitting method

ABSTRACT

A mobile station device that receives downlink control information which is used to selectively provide downlink scheduling or a random access order, on a physical downlink control channel from a base station device. The mobile station device also transmits a random access preamble using a random access channel to the base station device based on receiving the downlink control information which provides a random access order, where the downlink control information provides a downlink resource allocation in a case that the downlink control information is used to provide the downlink scheduling and where a preset value is set for a field of the downlink resource allocation in a case that the downlink control information is used to provide the random access order.

This application is a Continuation of Ser. No. 14/743,809, filed Jun.18, 2015, which is a Continuation of U.S. application Ser. No.14/098,048, filed on Dec. 5, 2013 (now U.S. Pat. No. 9,094,168, issuedon Jul. 28, 2015), which is a Continuation of U.S. application Ser. No.12/527,680 filed on Aug. 18, 2009 (now U.S. Pat. No. 8,681,716, issuedon Mar. 25, 2014), and for which priority is claimed under 35 U.S.C. §120, application Ser. No. 12/527,680 is the national phase of PCTInternational Application No. PCT/JP2008/060706 filed on Jun. 11, 2008under 35 U.S.C. § 371, which claims the benefit of priority ofJP2007-155289 filed Jun. 12, 2007. The entire contents of each of theabove-identified applications are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a base station device, a mobile stationdevice, a program, an uplink synchronization requesting method, and asynchronization-shift measurement signal transmitting method.Particularly, the present invention relates to a mobile station device,a program, an uplink synchronization requesting method, and asynchronization-shift measurement signal transmitting method for uplinktiming synchronization from the mobile station device to the basestation device.

Priority is claimed on Japanese Patent Application No. 2007-155289,filed Jun. 12, 2007, the content of which is incorporated herein byreference.

BACKGROUND ART

W-CDMA has been standardized by 3GPP (3rd Generation PartnershipProject), and services thereof have been sequentially provided. HSDPA(High Speed Downlink Packet Access) which is a faster communicationscheme has been also standardized and services thereof are about to beprovided.

Evolved Universal Terrestrial Radio Access (hereinafter, “EUTRA”) hasbeen under consideration by 3GPP. OFDM (Orthogonal Frequency DivisionMultiplexing) has been proposed for EUTRA downlink by 3GPP. DFT(Discrete Fourier Transform)-spread OFDM, which is a single-carriercommunication scheme, has been proposed for an EUTRA uplink.

FIG. 15 illustrates an EUTRA uplink-and-downlink channel structure.

An EUTRA downlink includes a DPiCH (Downlink Pilot Channel), a DSCH(Downlink Synchronization Channel), a Downlink Common Control Channel, aPDCCH (Physical Downlink Control Channel) (L1/L2 (Layer 1/Layer 2)Control Channel), and a DL-SCH (Downlink-Shared Channel).

An EUTRA uplink includes a UPiCH (Uplink Pilot Channel), a RACH (RandomAccess Channel), a UL-SCH (Uplink-Shared Channel), and a PUCCH (PhysicalUplink Control Channel) (see Non-Patent Document 1).

FIG. 16 illustrates an example of RACHs and UL-SCHs being allocated toradio resources. In FIG. 16, horizontal and vertical axes denote timeand frequency, respectively. FIG. 16 shows a structure of one radioframe which is divided into multiple radio resources. In this case, eachradio resource has a region defined by 1.25 MHz in the frequencydirection and 1 ms in the time direction. RACHs and UL-SCHs explained inFIG. 15 are allocated to these regions as illustrated. Thus, the minimumunit of a RACH has 1.25 MHz. In FIG. 16, UPiCHs are shatteringlyallocated in an UL-SCH region by symbol or subcarrier. Since multiplechannels are prepared for RACHs in EUTRA, multiple random accesses areavailable at the same time. Synchronization between a mobile stationdevice and a base station device is the primary purpose of the use ofRACHs. It has also been considered that a few bits of data forrequesting a scheduling of a radio resource assignment are transmittedover a RACH to reduce a connection time (see Non-Patent Document 2).

Only a preamble is transmitted over RACH for synchronization. Thepreamble includes a signature which is a signal pattern indicative ofinformation. From among tens of signatures preliminarily prepared, somesignatures are selected to configure a few bits of data. Currently, 6bits of data are transmitted by signatures in EUTRA. 64 (i.e., 2 to the6th power) signatures are prepared for 6 bits of data.

A random ID is assigned to 5 bits of 6 bits of signatures. Any ofinformation items concerning a random access reason, a downlink pathloss/CQI (Channel Quality Indicator), or the like, is assigned to theremaining 1 bit (see Non-Patent Document 3).

FIG. 17 is a sequence chart illustrating uplink synchronization usingRACH. First, a mobile station device selects a signature based on arandom ID, a random access reason, a downlink path loss/CQI, or thelike, and transmits a preamble including the signature over the RACH(message Ma1). Upon receiving the preamble from the mobile stationdevice, a base station device compares the preamble with a signalpattern preliminarily stored as a preamble to calculate asynchronization timing shift. Then, the base station device performs ascheduling for transmitting an L2/L3 (Layer 2/Layer 3) message, andallocates a C-RNTI (Cell Radio Network Temporary Identifier) to a mobilestation device determined to require the C-RNTI based on the randomaccess reason. Then, the base station device transmits a preambleresponse including synchronization timing shift information, schedulinginformation, the C-RNTI, and the random ID (message Ma2). The mobilestation device extracts the preamble response including the random IDwhich is transmitted from the base station device, and transmits anL2/L3 message using the scheduled radio resources (message Ma3). Uponreceiving the L2/L3 message, the base station device transmits, to themobile station device, a contention resolution for determining whetheror not a collision is occurring between mobile station devices (messageMa4) (see Non-Patent Document 3).

If multiple mobile station devices select the same signature and RACHfor random accesses, the random accesses of the mobile station devicescollide with one another. A sequence when a collision of random accessesoccurs is explained with reference to FIG. 17. If multiple mobilestation devices select the same signature and transmit preambles usingthe same radio resource block having the same time and frequency (i.e.,the same RACH), the messages Ma1 collide. If the base station devicecannot detect the message Ma1 due to the collision, the base stationdevice cannot transmit a preamble response (message Ma2). Since themobile station device cannot receive a preamble response (message Ma2)from the base station device, the mobile station device selects asignature and a RACH again after a given time interval, and thenperforms a random access. On the other hand, if the base station devicecan detect a preamble (Ma1) in spite of the collision, the base stationdevice calculates a scheduling for an L2/L3 message and asynchronization timing shift, and then transmits a preamble response(message Ma2) to the mobile station devices. However, all the mobilestation devices receive the preamble message, and then transmits anL2/L3 message (message Ma3) using the scheduled resource. Consequently,messages Ma3 from the mobile station devices collide. Since the basestation device cannot receive the L2/L3 message due to the collision,the base station device cannot transmit a response. Since none of themobile station devices receives a response to the L2/L3 message, each ofthe mobile station devices selects a signature again and then performs arandom access.

When uplink synchronization between the mobile station device and thebase station device is lost (for example, when data has not beenreceived or transmitted for a long period, and the mobile station deviceis, for a long period, in a DRX (Discontinuous Reception) state formonitoring a downlink resource assignment signal), and when the basestation device resumes a downlink data transmission, the mobile stationdevice cannot transmit an ACK/NACK (Acknowledgement/NegativeAcknowledgement) which is a reception response for an HARQ (HybridAutomatic Repeat Request). This is because the uplink synchronization islost, and therefore a transmission of the ACK/NACK for the HARQ causesan interference with another mobile station device. For this reason,uplink synchronization has to be established using a random access upona downlink data transmission resuming. However, there is concern that ittakes a long time for the downlink data transmission to be resumed if acollision occurs upon the random access. To prevent this, a propositionhas been made in which a collision of random accesses upon a downlinkdata transmission resuming is prevented by, for example, using asignature dedicated to a downlink data transmission resuming.

FIG. 18 is a sequence chart illustrating a method of preventing acollision of random accesses when a downlink data transmission isresumed.

When the base station device decides to resume a downlink datatransmission to a mobile station device with which uplinksynchronization is lost, the base station device transmits an uplinksynchronization request (message Mb1). This uplink synchronizationrequest is transmitted using an L1/L2 (Layer 1/Layer 2) control channel.The uplink synchronization request includes the signature ID number of arandom access to be performed by the mobile station device. This iscalled a dedicated signature. The mobile station device performs arandom access (i.e., transmits a preamble) using the dedicated signatureincluded in the received uplink synchronization request (message Mb2).Upon receiving the preamble including the dedicated signature, the basestation device detects a synchronization timing shift based on thepreamble. Then, the base station device transmits, as a preambleresponse, a TA (Timing Advance) command indicative of thesynchronization timing shift (message Mb3). After the base stationtransmits the TA command, the base station device transmits an L1/L2control channel including a downlink resource assignment (message Mb4),and then resumes a downlink data transmission (message Mb5) (seeNon-Patent Document 4).

Non-Patent Document 1: R1-050850 “Physical Channel and Multiplexing inEvolved UTRA Uplink”, 3GPP TSG RAN WG1 Meeting #42 London, UK, Aug.29-Sep. 2, 2005

Non-Patent Document 2: 3GPP TR (Technical Report) 25.814, V7.0.0(2006-06), Physical layer aspects for evolved Universal TerrestrialRadio Access (UTRA)

Non-Patent Document 3: 3GPP TS (Technical Specification) 36.300, V0.90(2007-03), Evolved Universal Terrestrial Radio Access (E-UTRA) andevolved Universal Terrestrial Radio Access Network (E-UTRAN), Overalldescription Stage 2

Non-Patent Document 4: R2-062165 “UL Synchronization”, 3GPP TSG RAN WG2Meeting #54 Tallinn, 28 Aug.-1 Sep. 2006

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In the method of resuming a downlink data transmission to prevent acollision of random accesses as explained above, an uplinksynchronization request is transmitted using a PDCCH (L1/L2 controlchannel) requiring no ACK/NACK for the HARQ. The PDCCH is a channel fortransmitting, between the base station device and the mobile stationdevice, adaptive modulation parameters for transmitting and receivinguser data, or channel allocation information. For this reason, a PDCCHis allocated to a fixed position of a radio resource and frequentlytransmitted.

A problem to be solved is that utilization efficiency of radio resourcesdegrades if a region to which an uplink synchronization request whichdoes not occur so often is allocated is saved in a PDCCH which isfrequently transmitted.

Means for Solving the Problems

A mobile station device of the present invention is included in a mobilecommunication system. The mobile station device includes: a receiverthat receives, from a base station device, a physical downlink controlchannel including a region to which radio resource assignmentinformation is set; and a transmitter that transmits, to the basestation device, a random access preamble, when detecting information toorder the random access from a predetermined region of the physicaldownlink control channel. The predetermined region includes the regionto which the radio resource assignment information is set.

A base station device of the present invention is included in a mobilecommunication system. The base station device includes: a transmitterthat transmits, to a mobile station device, a physical downlink controlchannel including a region to which radio resource assignmentinformation is set; and a detector that detects a random accesspreamble, the preamble being transmitted from the mobile station device.The transmitter includes, when ordering the random access to the mobilestation, information to order the random access in a predeterminedregion of the physical downlink control channel to be transmitted to themobile station device. The predetermined region includes the region towhich the radio resource assignment information is set.

A processing method of the present invention is provided for a mobilestation device included in a mobile communication system. The processingmethod includes: receiving, from a base station device, a physicaldownlink control channel including a region to which radio resourceassignment information is set; and transmitting, to the base stationdevice, a random access preamble, when detecting information to orderthe random access from a predetermined region of the physical downlinkcontrol channel. The predetermined region includes the region to whichthe radio resource assignment information is set.

A processing method of the present invention is provided for a basestation device included in a mobile communication system. The processingmethod includes: transmitting, to a mobile station device, a physicaldownlink control channel including a region to which radio resourceassignment information is set; and detecting a random access preamble,the preamble being transmitted from the mobile station device.Transmitting the physical downlink control channel includes including,when ordering the random access to the mobile station, information toorder the random access in a predetermined region of the physicaldownlink control channel to be transmitted to the mobile station device.The predetermined region includes the region to which the radio resourceassignment information is set.

Effects of the Invention

The base station device of the present invention allocates informationindicative of an uplink synchronization request addressed to the mobilestation device to a region in a radio frame where parameters used forsynchronous communication between the base station and the mobilestation device are set. Accordingly, the uplink synchronization requestcan be allocated to achieve an excellent utilization efficiency of radioresources.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a format of downlink control information to betransmitted to a mobile station device with which uplink synchronizationis maintained according to an embodiment of the present invention.

FIG. 2 illustrates a format of uplink control information to betransmitted to the mobile station device with which uplinksynchronization is maintained according to the embodiment.

FIG. 3 illustrates a format of downlink control information including anuplink synchronization request according to the embodiment.

FIG. 4 is a schematic block diagram illustrating a configuration of abase station device according to the embodiment.

FIG. 5 is a schematic block diagram illustrating a configuration of amobile station device according to the embodiment.

FIG. 6 is a sequence chart illustrating a process of the base stationdevice when transmitting an uplink synchronization request including adedicated signature.

FIG. 7 is a sequence chart illustrating a process of the base stationdevice of the embodiment when transmitting an uplink synchronizationrequest not including the dedicated signature.

FIG. 8 is a sequence chart illustrating a process of the mobile stationdevice of the embodiment when a CRC for PDCCH fails.

FIG. 9 is a sequence chart illustrating another process of the mobilestation device of the embodiment when a CRC for PDCCH fails, which isdifferent from the process shown in FIG. 8.

FIG. 10 is a flowchart illustrating an uplink synchronization requesttransmission process of the base station device of the embodiment.

FIG. 11 is a flowchart illustrating a random access reception process ofthe base station device of the embodiment.

FIG. 12 is a flowchart illustrating an uplink synchronization managementprocess of the mobile station device of the embodiment.

FIG. 13 illustrates, as a modification of the embodiment, a format whenan uplink synchronization request is allocated to a region of downlinkcontrol information.

FIG. 14 illustrates, as a modification of the embodiment, a format whenan uplink synchronization request is allocated to a region of uplinkcontrol information.

FIG. 15 illustrates a configuration of uplink and downlink channels inconventional EUTRA.

FIG. 16 illustrates an example of RACH and UL-SCH being allocated toradio resources in the conventional EUTRA.

FIG. 17 is a sequence chart illustrating an uplink synchronization usingRACH in the conventional EUTRA.

FIG. 18 is a sequence chart illustrating a method of preventing acollision of random accesses when a downlink data transmission isresumed in the conventional EUTRA.

DESCRIPTION OF REFERENCE NUMERALS

10 data controller

11 OFDM modulator

12 scheduler

13 channel estimator

14 DFT-S-OFDM modulator

15 control data extractor

16 preamble detector

17 signature managing unit

19 radio unit

20 DL scheduler

21 UL scheduler

30 upper layer unit

50 data controller

51 DFT-S-OFDM modulator

52 scheduler

53 OFDM demodulator

54 channel estimator

55 control data extractor

56 synchronization aligner

57 preamble generator

58 signature selector

59 radio unit

60 upper layer unit

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention is explained withreference to accompanying drawings. A radio communication system of theembodiment includes a base station device and multiple mobile stationdevices, similarly to EUTRA. In the embodiment, an “uplink” indicatescommunication connection from the mobile station device to the basestation device. Additionally, a “downlink” indicates a communicationconnection from the base station device to the mobile station device.The downlink of the embodiment includes the DPiCH, the DSCH, thedownlink common control channel, the PDCCH (L1/L2 (Layer 1/Layer 2)control channel), and the DL-SCH. The uplink of the embodiment includesthe UPiCH, the RACH, and the UL-SCH.

RACH is an uplink channel having a guard time. For this reason, even ifa mobile station device transmits RACH to the base station device withwhich uplink timing synchronization is not maintained, and if asynchronization shift is within the guard time, the transmission of theRACH is enabled without causing an interference with another channel. Asignature to be included in a preamble to be transmitted over the RACHcan be selected from 64 signatures. The mobile station device selectsone of the 64 signatures and includes the selected signature in apreamble.

The PDCCH (L1/L2 control channel) is allocated a fixed region in eachradio frame. The fixed region for downlink control differs from that foruplink control. Downlink control information and uplink controlinformation for each mobile station device are allocated to the downlinkcontrol region and the uplink control region, respectively.

A mobile station device receives information addressed to the mobilestation device from the control information transmitted from the basestation device. The control information includes parameters to be usedfor data communication (synchronous communication) between the basestation device and the mobile station device, such as resourceassignment information for each mobile station device (i.e., regions ina radio frame defined by frequency and time), adaptive modulationparameters, the HARQ, or the like.

FIG. 1 illustrates a format of downlink control information to betransmitted to the mobile station device with which uplinksynchronization is maintained. As shown in FIG. 1, the downlink controlinformation includes downlink resource assignment information (12 bitsfor indicating positions of resources allocated in downlink to themobile station device), MCS (Modulation and Coding Scheme) information(3 bits for specifying a modulation scheme or an encoding scheme), MIMO(Multiple Input Multiple Output) information (2 bits for specifying thenumber of antennas), the payload size (5 bits which is the size ofpayload included in a resource allocated in downlink), HARQ information(5 bits), and C-RNTI (Cell specific Radio Network Temporary Identity)(16 bits which is identification information for the base station toidentify a mobile station device). CRC (Cyclic Redundancy Check) for thedownlink control information is shared with the C-RNTI. In other words,if CRC is calculated for downlink control information including theC-RNTI region, a calculated value becomes the value of C-RNTI. Themobile station device calculates CRC for each downlink controlinformation item, and determines whether or not the downlink controlinformation is addressed to the mobile station device based on whetheror not the result of the CRC matches the value of C-RNTI.

FIG. 2 illustrates a format of uplink control information to betransmitted to the mobile station device with which uplinksynchronization is maintained. As shown in FIG. 2, the uplink controlinformation includes uplink resource assignment information (10 bits forspecifying positions of resources allocated in uplink to a mobilestation device), MCS information (3 bits for specifying a modulationscheme or an encoding scheme), the payload size (5 bits which is thesize of payload included in a resource allocated in downlink), RSF(reference signal Format) (2 bits which is a transmission format of areference signal), TPC (Transmission Power Control) (4 bits forindicating a transmission power), and C-RNTI. CRC of the uplink controlinformation is shared with C-RNTI. In other words, similar to thedownlink control information shown in FIG. 1, whether or not the uplinkcontrol information is addressed to the mobile station device isdetermined based on whether or not the calculated value of CRC matchesthe value C-RNTI of the mobile station device.

FIG. 3 illustrates a format of downlink control information including anuplink synchronization request, which is transmitted when uplinkre-synchronization is necessary, that is, when an uplinkre-synchronization factor is detected. As shown in FIG. 3, informationindicative of “no resource assignment” is allocated to the first 12 bitsto which resource assignment information is allocated whensynchronization is maintained. Upon detecting the information indicativeof “no resource assignment”, the mobile station device determines thatthe downlink control information indicates an uplink synchronizationrequest. After the region indicating “no resource assignment”, 3 bits ofa reserve region is allocated. When information other than an uplinksynchronization request can be transmitted by downlink controlinformation, a value for identifying information to be transmitted maybe allocated to the reserve region.

2 bits of data indicating a type of signature is allocated to a “type”region positioned after the reserve region. The type of signatureindicates a dedicated signature or a random signature. The dedicatedsignature is a signature to be used for a random access performed byonly a mobile station device specified by the uplink synchronizationrequest transmitted from the base station device. 6 bits of data forspecifying the signature ID number when the type of the signature is adedicated signature is allocated to a “signature” region positionedafter the “type” region. 4 bits of data for specifying a radio frameregion where the signature ID number specified by the “signature” regioncan be used is allocated to a “frame number” region positioned after the“signature” region. If a validity period or the like is preliminarilydefined by specification, an available radio frame region does not haveto be specified. Similar to the case where uplink synchronization ismaintained, the “C-RNTI” region positioned after the “frame number”region is a region for specifying identification information concerninga mobile station device targeted by the downlink control information. 16bits of data serving as CRC are allocated to the “C-RNTI” region.Similar to the downlink control information shown in FIG. 1, whether ornot the information is addressed to the mobile station device isdetermined based on whether or not a calculated value of CRC matches thevalue of C-RNTI of the mobile station device.

As shown in FIGS. 1 and 3, the downlink control information to betransmitted when uplink synchronization is maintained has the same bitnumber as the downlink control information to be transmitted when uplinkre-synchronization is required and an uplink synchronization request isrequired to be included. The predetermined number of downlink controlinformation items as shown in FIGS. 1 and 3 are allocated to a downlinkcontrol region of PDCCH. The number of information items shown in FIG. 1when uplink synchronization is maintained and the number of informationitems shown in FIG. 3 when an uplink synchronization request istransmitted are determined according to a communication condition. Inother words, downlink control information, which is used when uplinkre-synchronization is required and an uplink synchronization request istransmitted, is allocated to a region to which downlink controlinformation used when uplink synchronization is maintained is allocated.

FIG. 4 is a schematic block diagram illustrating a structure of the basestation. The base station includes a data controller 10, an OFDMmodulator 11, a scheduler 12, a channel estimator 13, a DFT-S-OFDMdemodulator 14, a control data extractor 15, a preamble detector 16, asignature managing unit 17, a radio unit 19, and an upper layer unit 30.The scheduler 12 includes a DL scheduler 20 and a UL scheduler 21. Inthe embodiment, each of the channel estimator 13 and the UL scheduler 21functions as a re-synchronization factor detector that detects an uplinkre-synchronization factor of each mobile station device. The OFDMmodulator 11 and the radio unit 19 function as a transmitter. The datacontroller 10 receives user data and control data from the upper layerunit 30. Based on an instruction from the scheduler 12, the datacontroller 10 maps the control data to the downlink common controlchannel, the DSCH, the DPiCH, and the PDCCH. Additionally, the datacontroller 10 maps transmission data to be transmitted to each mobilestation device to the DL-SCH. Further, the data controller 10 receivesuplink control information and downlink control information from thescheduler 12, and maps the received information to the PDCCH. In otherwords, the OFDM modulator 11 performs, on the data mapped by the datacontroller 10 to each channel, OFDM signal processing, such as datamodulation, a serial to parallel conversion, an IFFT (Inverse FastFourier Transform), a CP (Cyclic Prefix) insertion, a filtering, and thelike, to generate an OFDM signal. The radio unit 19 upconverts the OFDMsignal generated by the OFDM modulator 11 into a radio frequency signal,and transmits the converted signal to the mobile station device throughan antenna.

The radio unit 19 receives an uplink signal from a mobile station devicethrough the antenna. Then, the radio unit 19 downconverts the receivedsignal into a baseband signal, and then outputs the baseband signal tothe DFT-S-OFDM demodulator 14, the channel estimator 13, and thepreamble detector 16. The channel estimator 13 estimates radio channelcharacteristics from the UPiCH included in the received signal, andoutputs an estimation result to the DFT-S-OFDM demodulator 14. Thechannel estimator 13 outputs the estimation result to the scheduler 12for an uplink scheduling. Further, the channel estimator 13 detects anuplink synchronization shift and reports the detected uplinksynchronization shift to the scheduler 12 when uplink synchronization isnecessary. Although a single carrier scheme, such as DFT-spread OFDM, isconsidered as the uplink communication scheme, a multicarrier scheme,such as OFDM, may be used.

The DFT-S-OFDM demodulator 14 demodulates the reception signal receivedfrom the radio unit 19 using the radio channel characteristics receivedfrom the channel estimator 13, the resource assignment information,information concerning adaptive modulation parameters, and the like,which are received from the control data extractor 15. Thus, theDFT-S-OFDM demodulator 14 obtains reception data. The control dataextractor 15 divides the reception data into user data (UL-SCH) andcontrol data (PUCCH). The control data extractor 15 outputs downlink CQIinformation included in the control data to the scheduler 12, andoutputs the other control data and the user data to the upper layer unit30.

As explained above, the scheduler 12 includes the DL scheduler 20 thatperforms downlink scheduling and the UL scheduler 21 that performsuplink scheduling. The DL scheduler 20 performs a scheduling for mappinguser data to each downlink channel based on the CQI informationindicated by a mobile station device and scheduling information includedin each user data which is indicated by the upper layer unit 30. Basedon a scheduling result, the DL scheduler 20 generates downlink controlinformation shown in FIG. 1 to be transmitted to a mobile station devicewith which synchronization is maintained, and outputs the generateddownlink control information to the data controller 10. The UL scheduler21 performs a scheduling for mapping user data to each uplink channelbased on the uplink radio channel estimation result received from thechannel estimator 13 and the resource assignment request received fromthe mobile station device. Based on a scheduling result, the ULscheduler 21 generates uplink control information shown in FIG. 2 to betransmitted to a mobile station device with which synchronization ismaintained, and outputs the generated uplink control information to thedata controller 10.

The UL scheduler 21 manages uplink synchronization conditions of eachmobile station device using a timer, and detects, as an occurrence of anuplink re-synchronization factor, a mobile station device to/from whichdata has not been transmitted/received for a given time period. Withrespect to the mobile station device requiring uplink re-synchronizationwhich is detected using the timer and the mobile station devicerequiring uplink re-synchronization which is detected by the channelestimator 13, the UL scheduler 21 indicates a detection of the uplinkre-synchronization factor to the upper layer unit 30. At the same time,the UL scheduler 21 generates downlink control information including anuplink synchronization request for each of the mobile station devices,and outputs the generated downlink control information to the datacontroller 10. Upon generating the downlink control informationincluding the uplink synchronization request, the UL scheduler 21obtains the signature ID number of an available dedicated signature fromthe signature managing unit 17, and stores the obtained signature IDnumber in the downlink control information. At the same time, the ULscheduler 21 registers, in the signature managing unit 17, informationfor identifying a mobile station device that uses the signature IDnumber and the number of a radio frame to be used.

The preamble detector 16 detects a preamble that is a synchronizationshift measurement signal from the reception signal received from theradio unit 19, and calculates a synchronization timing shift. Thepreamble detector 16 indicates the signature ID number (measurementsignal identification information) obtained from the detected preamble,and indicates the calculated synchronization timing shift to the upperlayer unit 30. If the obtained signature ID number corresponds to thesignature indicated from the signature managing unit 17, the preambledetector 16 sets 1 to the dedicated signature flag. If the obtainedsignature ID number does not correspond to the signature indicated fromthe signature managing unit 17, the preamble detector 16 sets 0 to thededicated signature flag. Additionally, if the obtained signature IDnumber corresponds to the signature indicated from the signaturemanaging unit 17, the preamble detector 16 indicates to the signaturemanaging unit 17 that the preamble including the indicated signature IDnumber has been detected.

Based on an instruction from the UL scheduler 21, the signature managingunit 17 selects a dedicated signature and indicates the ID number of theselected dedicated signature to the UL scheduler 21. Additionally, thesignature managing unit 17 indicates the selected signature to thepreamble detector 16. Upon selecting a dedicated signature, thesignature managing unit 17 confirms the signature ID number of thededicated signature in use, and selects one from dedicated signaturesnot in use. The signature managing unit 17 registers the ID number ofthe selected signature as one in use, and deletes the signature detectedby the preamble detector 16 from stored information. The upper layerunit 30 controls the base station device based on a process as will beexplained later with reference to FIGS. 6 to 11.

FIG. 5 is a schematic block diagram illustrating a configuration of amobile station device. The mobile station device includes a datacontroller 50, a DFT-S-OFDM modulator 55, a scheduler 52, an OFDMdemodulator 53, a channel estimator 54, a control data extractor 55, asynchronization aligner 56, a preamble generator 57, a signatureselector 58, a radio unit 59, and an upper layer unit 60.

User data and control data are input to the data controller 50, andmapped to the UL-SCH based on an instruction from the scheduler 52. TheDFT-S-OFDM modulator 51 performs, on the data mapped by the datacontroller 50, DFT-S-OFDM signal processing, such as data modulation, aDFT conversion, a subcarrier mapping, an IFFT conversion, a CP (CyclicPrefix) insertion, a filtering, and the like. Thus, the DFT-S-OFDMmodulator 51 generates a DFT-Spread-OFDM signal. Although a singlecarrier scheme, such as DFT-spread OFDM, is considered as the uplinkcommunication scheme, a multicarrier scheme, such as OFDM, may be used.The synchronization aligner 56 determines a transmission timing based onthe synchronization information received from the control data extractor55. Then, the synchronization aligner 56 outputs the DFT-Spread-OFDMsignal received from the DFT-Spread-OFDM modulator 51 to the radio unit59 in time for the transmission timing. The radio unit 59 sets a radiofrequency to a value specified by the radio controller, upconverts theDFT-Spread-OFDM signal received from the synchronization aligner 56 intoa radio frequency signal, and transmits the radio frequency signal tothe base station device through an antenna.

The radio unit 59 receives a downlink signal from the base stationdevice through the antenna, downconverts the received signal into abaseband signal, and outputs the baseband signal to the OFDM modulator53 and the channel estimator 54. The channel estimator 54 estimatesradio channel characteristics from the DPiCH included in the signalreceived from the radio unit 59, and outputs an estimation result to theOFDM demodulator 53 and the scheduler 52. To indicate the radio channelcharacteristics estimation result to the base station device, thechannel estimator 54 converts the estimation result into CQI (ChannelQuality Indicator) information, and outputs the CQI information to thedata controller 50. The OFDM demodulator 53 demodulates the basebandsignal received from the radio unit 59 using the radio channelcharacteristics estimation result, and thus obtains reception data. Thecontrol data extractor 55 divides the reception data into user data andcontrol data.

The control data extractor 55 extracts uplink control informationaddressed to the mobile station device from the divided control data,and outputs the uplink control information to the scheduler 52. Further,the control data extractor 55 extracts uplink synchronizationinformation addressed to the mobile station device, and outputs theuplink synchronization information to the synchronization aligner 56.The control data extractor 55 extracts downlink control informationaddressed to the mobile station device from the divided control data. Ifthe extracted downlink control information is addressed to the mobilestation device with which uplink synchronization is maintained, thecontrol data extractor 55 instructs the OFDM demodulator 53 todemodulate, from the baseband signal, the user data and the control dataspecified by the resource assignment included in the downlink controlinformation based on a modulation scheme specified by the adaptivemodulation parameters included in the downlink control information. Onthe other hand, if the downlink control information addressed to themobile station device includes an uplink synchronization request, thecontrol data extractor 55 outputs the downlink control information tothe upper layer unit 60 for transmitting a synchronization shiftmeasurement signal based on the downlink control information.Additionally, the control data extractor 55 outputs the control data andthe user data other than the above downlink control information to theupper layer unit 60. Referring to the resource assignment region of thedownlink control information, the control data extractor 55 determineswhether the downlink control information is addressed to the mobilestation device with which uplink synchronization is maintained or thedownlink control information includes an uplink synchronization request.If allocated resources are specified, the control data extractor 55determines that the downlink control information is addressed to themobile station device with which uplink synchronization is maintained.If there is no allocated resource, the control data extractor 55determines that the downlink control information includes an uplinksynchronization request.

The signature selector 58 selects the signature ID number to be used fora random access based on an instruction from the upper layer unit 60,and outputs the selected signature ID number to the preamble generator57. The preamble generator (measurement signal generator) 57 generates apreamble (synchronization shift measurement signal), and outputs thegenerated preamble to the DFT-S-OFDM modulator 51. The scheduler 52performs MAC control to control data transmission and/or reception usingthe resources specified by the base station. Additionally, the scheduler52 manages uplink synchronization conditions of each mobile stationdevice using a timer. The upper layer unit 60 controls the mobilestation device based on a process as will be explained layer withreference to FIGS. 6 to 12.

In the embodiment, upon transmitting an uplink synchronization requestto a mobile station device requiring an uplink re-synchronization, thebase station device transmits an uplink synchronization request over thePDCCH. If a dedicated signature is included in the uplinksynchronization request, the mobile station device transmits a RACHusing the dedicated signature without a contention. The details areexplained hereinafter. FIG. 6 illustrates a process of the base stationdevice transmitting an uplink synchronization request including adedicated signature. FIG. 7 illustrates a process of the base stationdevice transmitting an uplink synchronization request in which a randomsignature is specified. FIG. 8 illustrates a process of the mobilestation device when the mobile station device cannot receive a PDCCHincluding an uplink synchronization request.

FIG. 6 is a sequence chart illustrating a process of the base stationdevice transmitting an uplink synchronization request including adedicated signature. The base station device manages uplinksynchronization with mobile station devices. The UL scheduler 21 of thebase station device sets a timer. If an uplink transmission has not beenperformed for a given time period, or if uplink synchronizationinformation has not been updated for a given time period, the ULscheduler 21 determines that an uplink re-synchronization factor occurs.If the channel estimator 13 receives uplink transmission data or atransmission signal from a mobile station device and detects a receptiontiming shift, the channel estimator 13 determines that an uplinkre-synchronization factor occurs. The base station device transmits anuplink synchronization request upon detecting an arrival of data(transmission data and reception data) addressed to the mobile stationdevice requiring a re-synchronization, that is, the mobile stationdevice for which it is determined that an uplink re-synchronizationfactor occurs. Alternatively, the base station device transmits anuplink synchronization request to the mobile station device upondetermining that uplink synchronization with the mobile station devicefor which it is determined that an uplink re-synchronization factoroccurs is to be maintained. The UL scheduler 21 generates downlinkcontrol information including an uplink synchronization request. Then,the data controller 10 maps the generated downlink control informationto the PDCCH to be transmitted (signal 6-1). The uplink synchronizationrequest has the format shown in FIG. 3. The uplink synchronizationrequest includes the signature ID number for specifying the dedicatedsignature that the UL scheduler 21 has obtained from the signaturemanaging unit 17. The signature ID number and the C-RNTI of the mobilestation device which is the transmission destination are correlated andstored in the signature managing unit 17.

The control data extractor 55 of the mobile station device calculates aCRC for each downlink control information item of the PDCCH to find oneidentical to the value of C-RNTI of the mobile station device. Thus, thecontrol data extractor 55 detects that the downlink control informationaddressed to the mobile station device is correctly received. Since “noresource assignment” is set to resource assignment information includedin the downlink control information, the control data extractor 55detects that the downlink control information indicates an uplinksynchronization request. Upon receiving the uplink synchronizationrequest, the upper layer unit 60 indicates the signature ID number andthe frame number which are specified by the uplink synchronizationrequest to the signature selector 58. The signature selector 58 selectsa dedicated signature corresponding to the specified signature IDnumber, and then indicates the dedicated signature and the specifiedframe number to the preamble generator 57. The preamble generator 57generates a preamble of the indicated dedicated signature. Then, theDFT-S-OFDM modulator 51 transmits the preamble using a RACH included ina radio frame corresponding to the specified frame number (signal 6-2:message 1).

When the preamble detector 16 of the base station device detects thepreamble on the RACH, the upper layer unit 30 generates a preambleresponse to the preamble, and transmits the generated preamble response(signal 6-3: message 2). At this time, the upper layer 30 of the basestation device compares the dedicated signature detected from thepreamble to the information registered in the signature managing unit17, and thereby can identify the mobile station device that hastransmitted the detected preamble. The upper layer unit 30 obtainsC-RNTI that is the identification information concerning the identifiedmobile station device from the signature managing unit 17. The datacontroller 10 maps the preamble response to PDCCH and DL-SCH. Theinformation mapped to the PDCCH includes RA-RNTI (Random Access-RadioNetwork Temporary Identity) for identifying the preamble response orC-RNTI for directly specifying a mobile station device. The informationmapped to the DL-SCH includes synchronization information indicative ofa synchronization shift alignment amount.

When the RA-RNTI is used, the dedicated signature or C-RNTI is includedin the DL-SCH. The control data extractor 55 of the mobile stationdevice detects the dedicated signature or the C-RNTI, and therebydetects the preamble response addressed to the mobile station device.The control data extractor 55 extracts the synchronization informationfrom the preamble response, and indicates the synchronization shiftalignment amount specified by the synchronization information to thesynchronization aligner 56. Then, the base station device resumes anormal data transmission (signal 6-4 and signal 6-5).

FIG. 7 is a sequence chart illustrating a process of the base stationdevice when the base station device does not transmit a dedicatedsignature. The base station device manages uplink synchronization withthe mobile station device. The UL scheduler 21 of the base stationdevice sets a timer. If an uplink transmission has not been performedfor a given time period or if uplink synchronization information has notbeen updated for a given time period, the UL scheduler 21 determinesthat an uplink re-synchronization factor occurs. Alternatively, when thechannel estimator 13 receives uplink transmission data or a transmissionsignal from a mobile station device and detects a reception timingshift, the channel estimator 13 determines that an uplinkre-synchronization factor occurs. When the base station device detectsan arrival of data (transmission data and reception data) addressed to amobile station device requiring uplink re-synchronization, or when thebase station device determines that uplink synchronization is to bemaintained with the mobile station device requiringuplink-resynchronization, the base station device transmits an uplinksynchronization request. The UL scheduler 21 generates downlink controlinformation including an uplink synchronization request and maps thegenerated information to PDCCH to be transmitted (signal 7-1). Upon theuplink synchronization request, a random signature is set to the “type”region, which indicates that a dedicated signature is not allocated.

The control data extractor 55 of the mobile station device calculates aCRC for each downlink control information item of the PDCCH to find oneidentical to the value of C-RNTI of the mobile station device. Thus, thecontrol data extractor 55 detects that the downlink control informationaddressed to the mobile station device is surely received. Since “noresource assignment” is set to resource assignment information includedin the downlink control information, the control data extractor 55detects that the downlink control information indicates an uplinksynchronization request. Upon receiving the uplink synchronizationrequest, the upper layer unit 60 instructs the signature selector 58 toselect a signature. The signature selector 58 randomly selects asignature corresponding to the signature ID number excluding thededicated signature, and then instructs the preamble generator 57 togenerate a preamble including the selected signature. The preamblegenerator 57 generates a preamble including the specified signature.Then, the DFT-S-OFDM modulator 51 transmits the generated preamble usingRACH (signal 7-2: message 1).

When the preamble detector 16 of the base station device detects thepreamble over the RACH, the upper layer unit 30 generates a preambleresponse to the detected preamble, and transmits the generated preambleresponse (signal 7-3: message 2). At this time, the upper layer 30 ofthe base station device cannot identify a mobile station device bydetecting a signature. The data controller 10 maps the preamble responseto PDCCH and DL-SCH. The PDCCH includes a RA-RNTI for identifying thepreamble response. The DL-SCH includes mapping information concerningsynchronization information and a signature, mapping informationconcerning a signature and a new C-RNTI (T-C-RNTI), and schedulinginformation for the mobile station device transmitting a message 3 thatis a response to the message 2.

At this time, the base station device cannot recognize why the mobilestation device has performed the random access to the base stationdevice. The mobile station device transmits the message 3 based on thescheduling information included in the message 2 (signal 7-4: message3). A C-RNTI for identifying the mobile station device that is thetransmission source is included in the message 3. Upon receiving themessage 3 including the C-RNTI, the base station device detects that themessage 3 is the response from the mobile station device specified bythe signal 7-1 since the message 3 has been transmitted based on thepreviously transmitted scheduling information. The base station devicetransmits a contention resolution as information for preventing acollision when each of multiple mobile station devices transmits thepreamble of the message 1 corresponding to the message 3 using the samesignature (signal 7-5: message 4). The new mobile station deviceidentification information T-C-RNTI specified in the message 2 by thebase station device is included in the PDCCH to which the message 4 isallocated. The mobile station device identification information detectedfrom the message 3 by the base station device is included in the DL-SCH.Then, the base station device resumes normal data transmission (signals7-6 and 7-7).

FIG. 8 is a sequence chart illustrating a process of the mobile stationdevice when a CRC for the PDCCH fails. The base station device managesuplink synchronization with mobile station devices by, for example,setting a time. If an uplink transmission has not been performed for agiven time period, or if uplink synchronization information has not beenupdated for a given time period, the base station device determines thatan uplink re-synchronization factor occurs. Alternatively, if the basestation device receives uplink transmission data or a transmissionsignal from a mobile station device and detects a reception timingshift, the base station device determines that an uplinkre-synchronization factor occurs. When the base station device detectsan arrival of data (transmission data and reception data) addressed tothe mobile station device requiring re-synchronization, or when the basestation device determines that uplink synchronization is to bemaintained with the mobile station device requiring uplinkre-synchronization, the base station device transmits an uplinksynchronization request to the mobile station device. The uplinksynchronization request is transmitted over the PDCCH (signal 8-1).

The control data extractor 55 of the mobile station device calculates aCRC for each downlink control information item of the PDCCH to find oneidentical to the value of C-RNTI of the mobile station device. However,it is assumed here that the downlink control information cannot becorrectly received due to a bad reception condition of the mobilestation device and the calculated CRC does not match the value ofC-RNTI. Since the uplink synchronization request cannot be detected, themobile station device suspends a reception until the next receptioncycle, and performs a reception of PDCCH. If the base station devicedoes not receive a response from the mobile station device within agiven window time (a response method differs according to conditions ofFIGS. 6 and 7), the base station device detects that the mobile stationdevice could not receive the uplink synchronization request. Upondetecting no reception from the mobile station device, the base stationdevice waits for the next transmission cycle, and then transmits anuplink synchronization request to the mobile station device requiringuplink re-synchronization, again (signal 8-2).

FIG. 9 is a sequence chart illustrating another process of the mobilestation device when a CRC for PDCCH fails. The base station devicemanages uplink synchronization with mobile station devices by, forexample, setting a time. If an uplink transmission has not beenperformed for a given time period, or if uplink synchronizationinformation has not been updated for a given time period, the basestation device determines that an uplink re-synchronization factoroccurs. Alternatively, if the base station device receives uplinktransmission data or a transmission signal from a mobile station deviceand detects a reception timing shift, the base station device determinesthat an uplink re-synchronization factor occurs. When the base stationdevice detects an arrival of data (transmission data and reception data)addressed to the mobile station device requiring re-synchronization, orwhen the base station device determines that uplink synchronization isto be maintained with the mobile station device requiring uplinkre-synchronization, the base station device transmits an uplinksynchronization request to the mobile station device. The uplinksynchronization request is transmitted over PDCCH (signal 9-1).

The control data extractor 55 of the mobile station device calculates aCRC for each downlink control information item of the PDCCH to find oneidentical to the value of C-RNTI of the mobile station device. However,it is assumed here that the downlink control information cannot becorrectly received due to a bad reception condition of the mobilestation device and the calculated CRC does not match the value of theC-RNTI. Since the mobile station device cannot detect an uplinksynchronization request, the mobile station device performs an uplinktransmission (signal 9-2). The uplink transmission is not a dynamicuplink transmission over PDCCH, but a data transmission over UL-SCH towhich a transmission scheme, transmission resources, and the like arepreliminarily set by, for example, RRC signaling at the Layer 3 level,or a transmission of CQI feedback over PUCCH. When the base stationdevice detects the uplink transmission, the base station device detectsthat the mobile station device could not receive the uplinksynchronization request. Upon detecting that the mobile station devicefailed the reception, the base station device transmits an uplinksynchronization request to the mobile station device requiring an uplinkre-synchronization, again (signal 9-3). Since the uplink transmission ofthe signal 9-2 is a transmission from the mobile station device withwhich uplink synchronization is lost, whether or not the base stationdevice can correctly detect the signal 9-2 depends on the transmissiontiming of the mobile station device or radio conditions. Therefore, thissequence functions as a supplemental sequence for the sequence explainedin FIG. 8.

FIG. 10 is a flowchart illustrating an uplink synchronizationtransmission process of the base station device. When the UL scheduler21 or the channel estimator 13 of the base station device detects anuplink re-synchronization factor and then determines to transmit anuplink synchronization request (Sa1), the UL scheduler 21 confirmswhether or not a dedicated signature can be allocated, referring to thesignature managing unit 17. If a dedicated signature can be allocated(Sa2: YES), the UP scheduler 21 selects a dedicated signature (Sa3).Then, the UL scheduler 21 generates downlink control informationincluding an uplink synchronization request. In the downlink controlinformation, a dedicated signature is registered in the “type” region,and the signature ID number of the selected dedicated signature isregistered in the “signature” region in step Sa3. Then, the datacontroller 10 maps the downlink control information to PDCCH to betransmitted (Sa4).

On the other hand, if the dedicated signature cannot be allocated instep S2 (Sa2: NO), the UL scheduler 21 generates downlink controlinformation including an uplink synchronization request in which arandom access signature is set to the “type” region. Then, the datacontroller 10 maps the downlink control information to PDCCH to betransmitted (Sa6). If the downlink control information including theuplink synchronization request is transmitted in step Sa4 or Sa6, theupper layer unit 30 determines whether or not the preamble detector 16has received a preamble that is a response to the uplink synchronizationrequest within a predetermined window time, that is, within a radioframe specified by the “frame number” of the uplink synchronizationrequest. If the preamble has not been received (Sa5: NO), the routinereturns back to step Sa2, and the uplink synchronization request processis performed again. On the other hand, if it is determined in step Sa5that the preamble has been received (Sa5: YES), the uplinksynchronization request transmission process ends.

FIG. 11 is a flowchart illustrating a random access reception process ofthe base station device. When the preamble detector 16 of the basestation device detects a preamble on RACH, the preamble detector 16refers to the signature managing unit 17 and determines whether or notthe signature included in the preamble is a dedicated signature (Sb1).If it is determined in step Sb1 that the signature is a dedicatedsignature, the preamble detector 16 indicates to the upper layer unit 30the synchronization shift measured upon detecting the preamble. Uponreceiving the synchronization shift, the upper layer unit 30 outputs tothe data controller 10 a preamble response including the synchronizationinformation concerning the synchronization shift. Then, the preambleresponse is transmitted (Sb2), and then the random access receptionprocess ends. On the other hand, if it is determined in step Sb1 thatthe signature is not a dedicated signature, the upper layer unit 30outputs a preamble response including synchronization information andthe scheduling information included in the message 3 shown in FIG. 7.Then, the preamble response is transmitted (Sb3), and a process ofreceiving the message 3 starts. If the message 3 is received (Sb4), theupper layer unit 30 confirms whether or not C-RNTI of the mobile stationdevice requesting uplink synchronization is included in the message 3(Sb5). If C-RNTI or another ID of a mobile station device other than themobile station device requesting uplink synchronization, a random accessprocess for another factor is performed (Sb5: NO). If C-RNTI of themobile station device requesting an uplink synchronization is detected(Sb5: YES), the upper layer unit 30 generates a message 4 shown in FIG.4, and outputs the generated message 4 to the data controller 10. Then,the message 4 is transmitted (Sb6), and the random access receptionprocess ends.

FIG. 12 is a flowchart illustrating an uplink synchronization managementprocess of the mobile station device. Upon detecting C-RNTI of themobile station device on PDCCH (Sc1), the control data extractor 55 ofthe mobile station device determines whether or not “no resourceassignment” is set to the resource assignment region to determinewhether or not it is an uplink synchronization request (Sc2). If it isdetermined in step Sc2 that it is not an uplink synchronization request(Sc2: NO), normal data transmission and/or reception are performed. Onthe other hand, if it is determined in step Sc2 that it is an uplinksynchronization request (Sc2: YES), the upper layer unit 60 receivingthe uplink synchronization request from the control data extractor 55obtains information indicative of the type of signatures from the “type”region included in the uplink synchronization request. Then, the upperlayer unit 60 determines whether or not a dedicated signature isincluded (Sc3), and suspends an uplink transmission.

If it is determined in step Sc3 that the dedicated signature is included(Sc3: YES), the upper layer unit 60 instructs, through the signatureselector 58, the preamble generator 57 to transmit a preamble includingthe dedicated signature. The preamble generator 57 generates a preambleincluding the dedicated signature, and outputs the generated preamble tothe DFT-S-OFDM modulator 51. Thus, the preamble is transmitted (Sc4).After the preamble including the dedicated signature is transmitted, themobile station device receives the message 2 shown in FIG. 6 which is aresponse to the preamble (Sc5). The control data extractor 55 obtainssynchronization information from the message 2, and then sets thesynchronization information to the synchronization aligner 56. Then, themobile station device continues data transmission and/or reception.

On the other hand, if it is determined in step Sc3 that a dedicatedsignature is not included (Sc3: NO), the upper layer unit 60 instructsthe signature selector 58 to select a signature. Upon receiving theinstruction, the signature selector 58 randomly selects a signature, andoutputs the signature ID number of the selected signature to thepreamble generator 57. The preamble generator 57 generates a preambleincluding the signature corresponding to the signature ID number, andoutputs the preamble to the DFT-S-OFDM modulator 51. Thus, the preambleis transmitted (Sc6). After transmitting the preamble including therandomly selected signature, the mobile station device receives themessage 2 shown in FIG. 7 which is a response to the preamble (Sc7). Themobile station device obtains, from the message 2, mapping informationconcerning synchronization information and a signature, mappinginformation concerning a signature and a new C-RNTI (T-C-RNTI), andscheduling information included in the message 3. The mobile stationdevice transmits the message 3 including the C-RNTI of the mobilestation device based on the obtained scheduling information (Sc8). Afterthe message 4 is received (Sc9), the mobile station device continuesdata transmission and/or reception.

Thus, in the embodiment, when uplink timing synchronization ismaintained between the base station device and the mobile stationdevice, an uplink synchronization request is included in downlinkcontrol information on PDCCH used for transmitting communicationparameters by setting “no resource assignment” to the resourceassignment region of the downlink control information, so that the setparameter is distinguished from that to be transmitted when uplinksynchronization is maintained. Thus, excellent utilization efficiency ofradio resources can be achieved. This method uses the fact thatcommunication parameters to be used when uplink synchronization ismaintained do not have to be transmitted since uplink re-synchronizationis always required for transmitting an uplink synchronization request,and the fact that “no resource assignment” does not have to betransmitted as a communication parameter to be used when uplinksynchronization is maintained.

The physical format of the PDCCH is used for both communicationparameters to be used when uplink synchronization is maintained, and anuplink synchronization request. For this reason, when the mobile stationdevice detects “no resource assignment” by data processing in a normalPDCCH reception process, it may be determined that it is an uplinksynchronization request. Therefore, the mobile station device has noneed to receive an uplink synchronization request by a specific physicalprocess. Thus, the mobile station device can receive an uplinksynchronization request by a normal data reception process. For thisreason, the base station device can transmit an uplink synchronizationrequest in any timing.

In the embodiment, an uplink synchronization request is set to a regionincluded in the downlink control information shown in FIG. 3. However,an uplink synchronization request may be set to a region included inuplink control information by setting “0” to the MCS or the payloadsize, or by setting information indicative of “no resource assignment”to 10 bits of data to which uplink resource assignment information is tobe set so that an uplink synchronization request can be identified, asshown in FIG. 14. Alternatively, an uplink synchronization request maybe identified by setting “0” to the MCS or the payload size included indownlink control information, as shown in FIG. 14.

Alternatively, an uplink synchronization request may be allocated toboth a region included in downlink control information and a regionincluded in uplink control information.

The upper layer unit 30, the data controller 10, the OFDM modulator 11,the scheduler 12, the channel estimator 13, the DFT-S-OFDM demodulator14, the control data extractor 15, the preamble detector 16, and thesignature managing unit 17, which are shown in FIG. 4; or the upperlayer unit 60, the data controller 50, the DFT-S-OFDM modulator 51, thescheduler 52, the OFDM demodulator 53, the channel estimator 54, thecontrol data extractor 55, the synchronization aligner 56, the preamblegenerator 57, and the signature selector 58, which are shown in FIG. 5,may be implemented by a program implementing the functions of thoseunits being stored in a computer readable recording medium, and by theprogram being read and executed by a computer system. The “computersystem” includes OS, and hardware, such as peripheral devices.

Additionally, the “computer system” includes home page provisionenvironments (or display environments) if a WWW system is used.

The “computer-readable recording medium” includes a portable medium,such as a flexible disk, an optical disc, a ROM, a CD-ROM, and the like,and a storage device such as a hard disk installed in a computer system.The “computer-readable recording medium” includes a medium dynamicallystoring a program for a short period, such as a communication line whena program is transmitted through a network such as the Internet or acommunication line such as a telephone line. Additionally, the“computer-readable recording medium” includes a medium storing a programfor a given period, such as volatile memory in a computer system of aserver or a client in the above case. The program may be forimplementing a part of the aforementioned functions or for implementingthe aforementioned functions with a combination of the program andanother program stored in the computer system.

As explained above, the following configurations can be made in theembodiment.

A base station device according to the embodiment includes: a datacontroller that generates data in which information indicative of anuplink synchronization request addressed to a mobile station device isset to a region on a radio frame to which parameters to be used forsynchronous communication with the mobile station device are set; atransmitter that transmits the data generated by the data controller;and a receiver that receives a signal for measuring a synchronizationshift based on the information indicative of the uplink synchronizationrequest, the signal being transmitted from the mobile station device.

The base station device further includes: a re-synchronization factordetector that detects an uplink re-synchronization factor of the mobilestation device. The data controller generates the data when there-synchronization factor detector detects the uplink re-synchronizationfactor.

In the base station device, the data controller generates data in whichthe information indicative of the uplink synchronization request andorder information concerning measurement signal identificationinformation to be included in the signal transmitted from the mobilestation device receiving the uplink synchronization request are set tothe region.

In the base station device, the order information is any one ofinformation to specify a value of the measurement signal identificationinformation and information to order the mobile station device to selecta value of the measurement signal identification information.

In the base station device, the region is a downlink shared controlchannel for downlink control.

A mobile station device according to the embodiment includes: a controldata extractor that refers to a region on a radio frame of a receptiondata, parameters to be used for synchronous communication with a basestation device being set to the region, and detects, when apredetermined value is set to a predetermined part of the region, thepredetermined value as information indicative of an uplinksynchronization request; a measurement signal generator that generates asignal for measuring a synchronization shift when the informationindicative of the uplink synchronization request is detected; and atransmitter that transmits the signal.

In the mobile station device, the control data extractor obtains, fromthe region, order information concerning measurement signalidentification information to be included in the signal when detectingthe information indicative of the uplink synchronization request.

In the mobile station device, the order information is any one ofinformation to specify a value of the measurement signal identificationinformation and information to order the mobile station device to selecta value of the measurement signal identification information. Themeasurement signal generator generates the signal including measurementsignal identification information having a value corresponding to theorder information.

In the mobile station device, the region is a downlink shared controlchannel for downlink control.

In the mobile station device, the transmitter transmits the signal usinga random access channel.

A method according to the embodiment is provided for a base stationdevice to request uplink synchronization. The method includes: a firststep of generating data in which information indicative of an uplinksynchronization request addressed to a mobile station device is set to aregion on a radio frame to which parameters to be used for synchronouscommunication with the mobile station device are set; a second step oftransmitting the data generated; and a third step of receiving a signalfor measuring a synchronization shift based on the informationindicative of the uplink synchronization request, the signal beingtransmitted from the mobile station device.

A method according to the embodiment is provided for a mobile stationdevice to transmit a signal for measuring a synchronization shift. Themethod includes: a first step of referring to a region on a radio frameto which parameters to be used for synchronous communication with a basestation device are set within reception data, and detecting, when apredetermined value is set to a predetermined part of the region, thepredetermined value as information indicative of an uplinksynchronization request; a second step of generating the signal whendetecting the information indicative of the uplink synchronizationrequest; and a third step of transmitting the signal.

Although the embodiment is explained with reference to the drawings,specific configuration is not limited to the embodiment, and variousmodifications can be made without departing from the scope of thepresent invention.

INDUSTRIAL APPLICABILITY

The present invention is suited to, but not limited to, a mobiletelephone system including a mobile telephone terminal as a mobilestation device.

What is claimed:
 1. A mobile station device included in a mobilecommunication system, the mobile station device comprising: a memory;and a processor coupled to the memory, the processor being configuredto: receive control information having a downlink control informationformat, on a physical downlink control channel from a base stationdevice, wherein the downlink control information format includes a firstfield to be used for downlink resource assignment, in a first case thata first value is set to the first field, the downlink controlinformation format is used for the downlink scheduling, in a second casethat a second value is set to the first field, the downlink controlinformation format is used for random access order, and the first valueis different from the second value.
 2. The mobile station deviceaccording to claim 1, the processor is further configured to: in thesecond case, transmit a random access preamble using a random accesschannel to the base station device in response to receiving the controlinformation.
 3. The mobile station device according to claim 1, whereinin the case second that a third value specifying a random accesspreamble is set to the downlink control information format.
 4. Themobile station device according to claim 1, wherein in the second case afourth value specifying a region on a radio frame available for therandom access is set to the downlink control information format.
 5. Abase station device included in a mobile communication system, the basestation device comprising: a memory; and a processor coupled to thememory, the processor being configured to: transmit control informationhaving a downlink control information format, on a physical downlinkcontrol channel to a mobile station device, wherein the downlink controlinformation format includes a first field to be used for downlinkresource assignment, in a first case that a first value is set to thefirst field, the downlink control information format is used for thedownlink scheduling, in a second case that a second value is set to thefirst field, the downlink control information format is used for therandom access order, and the first value is different from the secondvalue.
 6. The base station device according to claim 5, the processor isfurther configured to: in a second case, receive a random accesspreamble using a random access channel from the mobile station device inresponse to transmitting the control information.
 7. The base stationdevice according to claim 5, wherein in the second case a third valuespecifying a random access preamble is set to the downlink controlinformation format.
 8. The base station device according to claim 5,wherein in the second case a fourth value specifying a region on a radioframe available for the random access is set to the downlink controlinformation format.
 9. A processing method for a mobile station deviceincluded in a mobile communication system, the processing methodcomprising: receiving control information having a downlink controlinformation format, on a physical downlink control channel from a basestation device, wherein the downlink control information format includesa first field to be used for downlink resource assignment, in a firstcase that a first value is set to the first field, the downlink controlinformation format is used for downlink scheduling, in a second casethat a second value is set to the first field, the downlink controlinformation format is used for the random access order, and the firstvalue is different from the second value.
 10. The processing methodaccording to claim 9, the processing method further comprising: in asecond case, transmitting a random access preamble using a random accesschannel to the base station device in response to receiving the controlinformation.
 11. A processing method for a base station device includedin a mobile communication system, the processing method comprising:transmitting control information having a downlink control informationformat, on a physical downlink control channel to a mobile stationdevice, wherein the downlink control information format includes a firstfield to be used for downlink resource assignment, in a first case thata first value is set to the first field, the downlink controlinformation format is used for downlink scheduling, in a second casethat a second value is set to the first field, the downlink controlinformation format is used for random access order, and the first valueis different from the second value.
 12. The processing method accordingto claim 11, the processing method further comprising: in the secondcase, receiving a random access preamble using a random access channelfrom the mobile station device in response to transmitting the controlinformation.